1. Field Of The Invention
This invention relates to a switching equipment and, more particularly, to a switching equipment employing magnetic domains.
2. Description Of The Prior Art
Generally, switching is roughly divided into so-called channel switching which involves physical connections of circuits and time slot switching which rearranges the order of time slots in one signal frame of a PCM pulse signal or the like. The channel switching system is classified into one which employs, as a communication line switch, mechanical contacts such as reed relays or crossbar switches and one which employs electronic contacts such as transistors or diodes. The system of the type using the mechanical contacts has a problem in the reliability of the contacts and has the defects of a bulky structure and a low operating speed, whereas the system employing the semiconductor contacts has the drawbacks of expensiveness, low reliability, bulkiness because of requiring transformers on both sides of incoming and outgoing lines and presents problems in crosstalk and the low on-off ratio of the switch. For the time slot switching, it is considered possible to adopt such a method without using magnetic bubbles in which signals of one frame are stored in a memory and read out thereof in the order to time slots to be rearranged, but this method involves complicated operations for determing the reading-out order of the signals from the memory and hence requires much time. This technique is disclosed in the article: "Switching Networks of Planar Shifting Arrays," by R. S. Krupp and L. A. Tomko, The Bell System Technical Journal, July-August, 1973, pp. 991-1007. To overcome such defects, there has been proposed a method of using magnetic bubbles for the time slot switching, such as disclosed in the publication: IEEE TRANSACTIONS ON MAGNETICS, May 1977, Volume MAG-13, Number 3, pp. 969-972, but this conventional method is not suitable for a high-speed switching operation because of a low transfer speed of the magnetic bubble.